twa testing in the ep lab
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TWA Testing in the EP Lab. To guide performance of EP study To guide interpretation of EP study To provide independent information along with the EP study. TWA Testing in the EP Lab. To guide performance of EP study “Universal stimulation protocol” NASPE Task Force, 1985 - PowerPoint PPT PresentationTRANSCRIPT
TWA Testing in the EP LabTWA Testing in the EP Lab
To guide performance of EP study To guide interpretation of EP study To provide independent information
along with the EP study
TWA Testing in the EP LabTWA Testing in the EP Lab To guide performance of EP study “Universal stimulation protocol”– NASPE Task Force, 1985– 90% sensitivity in pts with a history of sustained VT and
prior MI– 1, 2, and 3 VPDs with at least two drive train cycle
lengths at each of two ventricular sites – “Additional pacing sites, including left ventricular sites,
should be considered if clinically appropriate and associated with an acceptable risk/benefit ratio”
– Pharmacologic stimulation (e.g. isoproterenol/dobutamine) not standardized
Bayesian ProbabilitiesBayesian Probabilities
Use pre-test TWA results to guide aggressiveness of stimulation protocol, to optimize predictive value of EPS– Third site?– Iso/Dobutamine at 1 or 2 sites?
TWA Testing in the EP LabTWA Testing in the EP Lab
To guide performance of EP study To guide interpretation of EP study– Rapid monomorphic VT
– Polymorphic VT/VF
Rapid Monomorphic VTRapid Monomorphic VT “Ventricular flutter” Regarded by many as a nonspecific response to
stimulation protocol– MUSTT excluded induced VTs with cycle length <
220 msec (if “no isoelectric interval between consecutive QRS complexes”)
However, in analyzing pts undergoing ICD implant for syncope and inducible VT, we found no difference in the subsequent event rate comparing pts with and without very rapid monomorphic VT
Ventricular FibrillationVentricular Fibrillation Accepted as positive endpoint in
MADIT/MUSTT if induced with single/double VPDs
Known to have low specificity with triple VPDs ACC/AHA ICD Implant Guidelines:– Syncope of undetermined origin with “clinically
relevant” sustained VF– “Inducible VF” in pts with nonsustained VT and
coronary disease, prior MI, and LV dysfunction
ALAL
61 year old F Ischemic cardiomyopathy (LVEF: 15%)– Severe triple vessel disease and 4+ MR
– Awaiting transplant (Class III CHF) Telemetry: 5 bt NSVT
AL TWA ResultsAL TWA Results
AL EPS ResultsAL EPS Results
Long runs of self-terminating monomorphic VT (nonsustained)
VF with triple VPDs from RVOT
ICD implanted
JHJH
56 year old M Mild LV dysfunction following MI and
PTCA of LAD (LVEF: 40%) 2 runs of NSVT (up to 10 beats) during a
stress test– Fixed apical and anterior defects
JH TWA ResultsJH TWA Results
JH EPS ResultsJH EPS Results
Rapid sustained monomorphic VT (CL: 213 msec) induced with triple VPDs from the RVOT
ICD implanted
TWA Testing in the EP LabTWA Testing in the EP Lab
To guide performance of EP study To guide interpretation of EP study To provide independent information
along with the EP study– Discordant results:» (-) TWA / (+) EPS
» (+) TWA/ (-) EPS
Is EPS the Gold Standard?Is EPS the Gold Standard?
MUSTT: (+) EPS 2yr Cardiac Arrest/Arrhythmic Death = 18%
18%
MUSTT: (-) EPS 2yr Cardiac Arrest/Arrhythmic Death = 12%
12%
4 out of 5 (+) EPS pts will not have an event in 2 years
1 out of 8 (-) EPS pts will have an event in 2 years
Buxton et al, NEJM 2000; 342 (26):1937
Risk-Stratification: TWA/EPSRisk-Stratification: TWA/EPS 215 pts undergoing EPS/TWA for
known/suspected arrhythmias– 60% syncope/presyncope– 27% prior sustained ventricular arrhythmia– 6% NSVT
400 Day Rate of VT or Death:– EPS (+): 25% EPS (-): 10%– TWA (+):26% TWA (-): 3%
Gold et al, J Am Coll Cardiol 2000;36:2247
NSVT Pts: TWA vs. EPSNSVT Pts: TWA vs. EPS Prior studies have looked at
heterogeneous populations (e.g. including pts with prior sustained arrhythmias)
We recently evaluated a homogenous population of 54 consecutive pts referred for EPS due to NSVT in the setting of CAD and LVEF 40%.
All pts underwent EPS with TWA testing
Cohen et al, ACC, 2001
Results: TWA vs. EPSResults: TWA vs. EPS
36 pts (67%) had (+) EPS 21 pts (39%) had (+) TWA vs. 20 (37%) (-) TWA and 13
(24%) indeterminate Excluding indeterminates, 18/41 discordant studies (44%) Prospective f/u ongoing to determine risk in TWA(-)/EPS(+)
and TWA(+)/EPS(-) pts
EPS (+) EPS (-) TotalTWA (+) 15 6 21TWA (-) 12 8 20TWA (indeterminate) 9 4 13Total 36 18 54
Event Rates of EPS and TWAEvent Rates of EPS and TWA
Singly In Combination
EPS+25% EPS+, TWA+39%
TWA+25% EPS-, TWA+ 15%
EPS- 5% EPS+, TWA-12%
TWA- 1.5% EPS-, TWA- 0%
Gold MR, et al. (FDA-Cleared Labeling, Cambridge Heart, Inc. K No. 983102).
WKWK
82 year old M Nonischemic cardiomyopathy Class III CHF LBBB 4 beats NSVT
WK TWA ResultsWK TWA Results
WK EPS ResultsWK EPS Results
HV interval (79 msec, nl < 55) VF with triple VPDs from RVOT
ICD with Biventricular pacing capability implanted
Implant EconomicsImplant Economics
Review of ICDs by insurers (esp. Medicare) is strict!– Expect close scrutiny
of implants that do not adhere to ACC/AHA guidelines
ConclusionsConclusions
TWA testing routine part of “VT study” Guide stimulation protocol Help interpret ambiguous results Identify high-risk patients despite
negative EP study